Eight people plan to share equally the cost of a rental car. If one withdraws and the remaining seven share the entire cost equally, by how much does each share increase?

Given data

• Total cost = C.
• Original share = C/8; new share (after one withdraws) = C/7.

Concept / Approach

• The increase is the difference between the new and old per-person shares.

Step-by-step calculationIncrease = C/7 − C/8 = C(1/7 − 1/8)= C((8 − 7)/56) = C/56

InterpretationEach remaining person pays an extra one fifty-sixth of the total cost.

Common pitfalls

• Reporting the increase relative to the old share instead of the total cost; the question asks for the absolute increase in terms of total cost.

Final Answer1/56 of the total cost